(a) Field of the Invention
The present invention relates to an AC plasma display panel (AC-PDP) for use in a flat panel television set and in a flat panel display unit, more in detail to the AC-PDP which realizes a high emission efficiency and improves display drive performance.
(b) Description of the Related Art
A color plasma display excites a fluorescent substance to make an emission display by means of a ultraviolet ray generated by gas discharge, and an application of the display panel to a large-screen television set is expected. Various systems have been developed for the color PDPs among which a reflection-type AC coplanar switching plasma display panel (AC-IPS-PDP) is excellent in its brightness and ease of manufacture.
FIGS. 1A to 1C show a typical reflection-type ACIPS-IPS-PDP. FIG.1A is an elevational view partially in section of a rear substrate, FIG. 1B is a side sectional view of a front substrate and FIG. 1C is a horizontal sectional view of the rear substrate.
A front substrate 100 disposed at a display side has a plurality of stripe transparent electrodes 13 and a plurality of narrow bus electrodes 14 extending in parallel on a glass substrate 11. An indium-tin oxide thin film or a tin oxide thin film is employed as the transparent electrode 13 which results in a large resistance of the transparent electrode 13. For compensating the large resistance of the transparent electrode 13, the bus electrode 14 is made from a good conductor metal such as silver in the form of a thick film, copper, aluminum and chromium in the form of a thin film to provide a high discharge current for sufficient emission in a large display unit. A dielectric layer 18 and a protection layer 19 are formed on the transparent electrode 13 and the bus electrode 14. The dielectric layer 18 may be formed as a transparent insulation layer having a thickness of about 20 to 40 micrometers by applying low melting point glass paste to the glass substrate 11 and sintering the glass substrate 11 at a high temperature slightly below 600xc2x0 C. The protection layer 19 is formed by, for example, vacuum-evaporation of a magnesium oxide to form a thin film having a large secondary electron radiation coefficient and an excellent anti-sputtering ability.
After stripe data electrodes 16 are formed on a glass substrate 12, a dielectric layer 21 including low-melting point glass as a main component is formed. After stripe partition walls 17 are formed, powdery fluorescent substances 20 of red, green and blue are sequentially applied on a bottom surface and a side surface of a trench formed by the partition walls 17 to complete a rear substrate 200. The partition walls 17 not only secure a discharge space but also prevent cross-talk of the discharge and seepage of a luminous color, and ordinarily have a width of 30 to 100 micrometers and a height of 60 to 200 micrometers. After the rear substrate 200 and the front substrate 100 are coupled and the periphery of the both substrates is sealed with frit glass, a panel is completed by heating the substrates, exhausting an inner gas and finally enclosing a discharge gas having a rare gas as a main component therein.
A pair of the transparent electrodes 13 are separated by a discharge gap 23. One of the transparent electrodes acts as a scanning electrode 31 and the other acts as a maintaining electrode 32, and various voltage waveforms are applied to the two transparent electrodes and the data electrode for driving.
A simple example of a basic driving of the electrodes is shown in FIG. 2. Data pulses having a polarity reverse to the polarity of scanning pulses are applied to the data electrode 16 depending on display data of the scanning electrode in the cell in timing with the scanning pulses having a negative polarity sequentially applied to the selected scanning electrode 31 Thereby, a counter discharge occurs between the scanning electrode 31 and the data electrode 16 The counter discharge as a trigger generates a surface discharge between the maintaining electrode 32 and the scanning electrode 31 to complete a write operation. The write discharge generates a wall charge on the surfaces of the maintaining electrode 32 and the scanning electrode 31. While the maintaining discharge for the surface discharge is generated by the maintaining pulse applied between the maintaining electrode 32 and the scanning electrode 31 during a maintaining period in the cell in which the wall charge is formed, the maintaining discharge is not generated in the cell in which the write operation is not conducted even if a maintaining pulse is applied because electric fields generated by the wall charges are not superimposed. The application of the desired number of the maintaining pulses generates a specified emission display. Gray scale display can be realized by repeating the write operation and the maintaining discharge operation every sub-field. A preliminary discharge operation in which compulsory discharge is conducted by applying high voltages to all cells may be employed before the write operation as shown in FIG. 2 for elevating performance of the write operation. Although the driving system of separating the scanning emission and the maintaining emission is illustrated in FIG. 2, various driving systems have been proposed including a system in which the scanning pulse and the maintaining pulse are combined.
JP-A-8(1996)-315735 or JP-A-8(1996)-250029 describes a prior art of the PDP.
FIG. 3 shows another conventional AC plasma display panel having a coupling part 15, and FIG. 4 shows a conventional electrode structure.
In order to employ the AC color plasma display in a wide range of use such as in a television for home use in the prior art, a display driving performance may be, however, reduced even when an improved structure is employed for elevating an emission efficiency.
With increase of resolution and the number of display gray scales, an accurate write operation in a short period of time is required, a writing on one scanning electrode 31 in a full-color panel having 480 scanning electrodes is required to be performed in 3micro-seconds, and a write operation in a higher resolution panel such as that in a high precision television is required to be performed in 2 micro-seconds. However, in the conventional electrode structure, a position of starting counter discharge at a time of the write operation between the data electrode 16 and the scanning electrode 32 and a position of strong discharge are scattered on a whole part formed by overlapping between the scanning electrode 31 and the data electrode 16. Accordingly, the write condition does not become uniform to make a flicker, or to generate write inferiority on the entire panel in an extreme case only to perform impractical display. High electricity consumption also becomes obvious.
In view of the foregoing, an object of the present invention is to provide an AC-PDP which realizes an emission display having high brightness and reduction of power dissipation by improving an emission efficiency.
Another object is to provide an AC-PDP in which a write operation can be securely conducted in a short period of time and has low power dissipation by devising a data electrode shape.
The present invention provides, in a first aspect thereof, an AC plasma display panel including: first and second glass substrates; a plurality of partition walls sandwiched between said first glass substrate and said second glass substrate, said partition walls extending in a column direction to separate a plurality of discharge cells in a row direction; a pair of transparent electrodes for extending in said row direction parallel to each other with a discharge gap therebetween in each of said discharge cells to operate surface discharge (in-plane discharge) therebetween; a plurality of metallic bus electrodes each disposed on said first glass substrate corresponding to each of said transparent electrodes, each of said transparent electrodes including a discharge part and a coupling part in each of said discharge cells, said coupling part coupling said discharge part to one of said metallic bus electrodes and coupling two of said discharge part disposed in adjacent two of said discharge cells; and a data electrode disposed on said second glass substrate to extend in each of said discharge cells in said column direction, said data electrode and said discharge part of a corresponding one of said transparent electrodes operating preliminary discharge therebetween.
The present invention provides, in a second aspect thereof, an AC plasma display panel including: first and second glass substrates; a plurality of partition walls sandwiched between said first glass substrate and said second glass substrate, said partition walls extending in a column direction to separate a plurality of discharge cells in a row direction; a pair of transparent electrodes for extending in said row direction parallel to each other with a discharge gap therebetween in each of said discharge cells to operate surface discharge therebetween; and a data electrode disposed on said second glass substrate to extend in each of said discharge cells in said column direction, said data electrode having a first width adjacent to said discharge gap and a second width adjacent to a side of said transparent electrode opposite to said discharge gap, said first width being larger than said second width.
In accordance with the electrode structure of the first aspect of the present invention, since the discharge part of the transparent electrode is separated from the bus electrode and the partition wall, a high emission efficiency can be obtained. Although the display discharging electrode is isolated in the discharge cell, the entire transparent electrode may have a connected structure and can be electrically connected with the bus electrode by way of a plurality of the coupling parts, and a dark defect liable to be generated in an isolated electrode structure is hardly generated.
In accordance with the electrode structure of the second aspect of the present invention, since the counter discharge for writing always occurs near the surface discharging gap of the scanning electrode by employing the data electrode having a specified shape, a high resolution panel with full-color display which requires higher-speed writing can be realized. An electrostatic capacity of the data electrode can be reduced while improving the write performance in the data electrode structure of the second aspect, and reduction of electricity consumption which may be a serious problem in a high resolution large picture panel can be realized.
The above and other objects, features and advantages of the present invention will be more apparent from the following description.